Claude 24f816b6a3
Consolidate 22 sibling repos into layered organism structure
Place useful parts of the surrounding repos into sica-fondt by layer, per the
body model (Ada = membrane; brain/endocrine/capabilities/knowledge non-Ada):

- brain/        LLM reasoning + providers (dapr, hermes, MoMoA)
- capabilities/ REPRAG sidecars: hermes tools/skills, dapr tools, parallel
                dispatch, A51 channels, and the OSINT cluster
- knowledge/    LORAG corpus: 754 cyber-skills, agency personas, secure-coding,
                MITRE ATT&CK data
- reference/    defensive threat-reference (C3, shhbruh doc) + AdaYaml parser

License handling: AGPL sources (worldosint, advanced_evolution, mercury,
Reticulum) and GPL DeTTECT are SPEC-only clean-room/port descriptions — no
copyleft code copied. MIT/Apache/data parts copied as working trees.

Safety: shhbruh escape/persistence material and C3 covert-C2 kept as reference
only, not wired into the running organism. See CONSOLIDATION.md.

https://claude.ai/code/session_01UehUqEXXJJCsHoA4voCU5c
2026-06-10 06:53:01 +00:00

3.1 KiB

name description domain subdomain tags version author license nist_csf
implementing-end-to-end-encryption-for-messaging End-to-end encryption (E2EE) ensures that only the communicating parties can read messages, with no intermediary (including the server) able to decrypt them. This skill implements a simplified version cybersecurity cryptography
cryptography
encryption
e2e
messaging
signal-protocol
1.0 mahipal Apache-2.0
PR.DS-01
PR.DS-02
PR.DS-10

Implementing End-to-End Encryption for Messaging

Overview

End-to-end encryption (E2EE) ensures that only the communicating parties can read messages, with no intermediary (including the server) able to decrypt them. This skill implements a simplified version of the Signal Protocol's Double Ratchet algorithm, using X25519 for key exchange, HKDF for key derivation, and AES-256-GCM for message encryption.

When to Use

  • When deploying or configuring implementing end to end encryption for messaging capabilities in your environment
  • When establishing security controls aligned to compliance requirements
  • When building or improving security architecture for this domain
  • When conducting security assessments that require this implementation

Prerequisites

  • Familiarity with cryptography concepts and tools
  • Access to a test or lab environment for safe execution
  • Python 3.8+ with required dependencies installed
  • Appropriate authorization for any testing activities

Objectives

  • Implement X25519 Diffie-Hellman key exchange for session establishment
  • Build the Double Ratchet key management algorithm
  • Encrypt and decrypt messages with per-message keys
  • Implement forward secrecy (compromise of current key does not reveal past messages)
  • Handle out-of-order message delivery
  • Implement key agreement using X3DH (Extended Triple Diffie-Hellman)

Key Concepts

Signal Protocol Components

Component Purpose Algorithm
X3DH Initial key agreement X25519
Double Ratchet Ongoing key management X25519 + HKDF + AES-GCM
Sending Chain Per-message encryption keys HMAC-SHA256 chain
Receiving Chain Per-message decryption keys HMAC-SHA256 chain
Root Chain Derives new chain keys on DH ratchet HKDF

Forward Secrecy

Each message uses a unique encryption key derived from a ratcheting chain. After a key is used, it is deleted, ensuring that compromise of the current state does not reveal previously sent/received messages.

Security Considerations

  • Delete message keys immediately after decryption
  • Implement message ordering and replay protection
  • Use authenticated encryption (AES-GCM) for all messages
  • Protect identity keys with device-level security
  • Verify identity keys out-of-band (safety numbers)

Validation Criteria

  • X25519 key exchange produces shared secret
  • Messages encrypt and decrypt correctly between two parties
  • Different messages produce different ciphertexts
  • Forward secrecy: old keys cannot decrypt new messages
  • Out-of-order messages can be decrypted
  • Tampered messages are rejected by authentication